The present invention is directed to an ink printer head including a head part, having ink ejection channels, that is cast into an outer mount with a rubber-elastic casting compound. The surface thereof is provided with an adhering, water-repelling silanization layer on a side of the discharge openings of the ink ejection channels.
In ink printer devices, the ejection of individual droplets from the discharge openings of the ink printer head is accomplished through the use of individually controllable drive elements. For example, small tubes composed of piezo-ceramic can be used as drive elements. The small tubes cylindrically surround the ink channels. No. DE-A-35 00 820 discloses an example of such a device. In what is known in the art as bubble-jet ink printer heads, heating elements that heat the liquid in the ink channel and cause the droplets to be ejected therefrom due to the formation of small bubbles are used as drive elements. No. DE-A-29 43 164 discloses an example of such a device.
With respect to the printer heads of ink printer devices the individual droplets ejected from the ink ejection channels are separated from the nozzle surface. This can be facilitated, for example, by creating the surface of the head parts so that they are non-moistenable by the ink on the side of the discharge openings of the ink ejection channels. This procedure also prevents ink from running out of the ink ejection channels and trickling onto the ink printer head when the printer device is idle.
It is known to use aqueous inks to cause the surfaces of the head parts to be water-repellant on the side of the ink discharge openings. Hydrophobic behavior is thereby achieved in that the surfaces are silanized, by chemically anchoring trimethyl siloxyl groups on the face-side surfaces by treating the head parts, preferably composed of glass, quartz, oxide ceramic or silicon, with a silylization agent such as trimethyl chlorosilane or hexamethyl disilazane.
The face-side surfaces are coated with a monomolecular, water-repelling layer. The chemical anchoring proceeds through Si--O--/Si elements or via Si--O--Al elements given aluminum oxide ceramic. However, these bonds are not completely hydrolysis-stable, and accordingly, the water-repelling effect decreases over time due to the lasting influence of the aqueous inks.